sterling



(No Model.) 2 Sheets-Sheet 1.

' W. A. STERLING..

RHEOSTAT.

Patented May 17, 1892.

I I I I INV TOR (No Model.) 2 sheets-sheet 2. W. A. STERLING.

RHEOSTAT.

.No. 475,255. Patented May 17, 1892.

w 75 I jgvl/Egrfi I w 1%. 41/ ATTORNEY.

UNITED STATES PATENT OFFICE.

\VALTER A. STERLING, OF DENVER, COLORADO, ASSIGNOR OF ONE-HALF TO GEORGE H. CAMPBELL, OF SAME PLACE.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 475,255, dated May 17, 1892.

Application filed November 6, 1891. Serial No. 411,107- (No model.)

T at whom it may concern.-

Be it known that I, WALTER A. STERLING, a citizen of the United States of America, residing at Denver, in the county of Arapahoe and State of Colorado,have invented certain new and useful Improvements in Rheostats; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference beinghad to the accompanying drawings, and to the figures of reference marked thereon, which form a part of this specification.

My invention relates to improvements in rheostats for controlling the brilliancy of incandescent electric lamps; and its object is to provide a device of the class stated which shall be of simple and economical construction, easily operated, reliable, durable, and eflicient in use.

To these ends the invention consists of the features hereinafter described and claimed.

' bottom plate 3.

In the accompanying drawings is illustrated an embodiment of my improved rheostat, in which- Figure l is a side elevation of the device; Fig. 2, a top or plan View; Fig. 3, a section on the line 1 y, Fig. 2; Fig. 4, a section on the line 00 on, Fig. 3; and Fig. 5, an elevation, on a small scale, showing the manner of attaching the rheostat to the wall of the room. Fig. 6 shows the rheostat located in the lamp-circuit.

In the views, similar reference characters indicating corresponding parts or elements of the mechanism,the numeral 2 designates the side Walls of a Small liquid-containing jar. The body 2 of this jar is composed of some suitable insulating material, preferably glass, to which is sealed a metallic bottom 3 and a metallic top 4. Parts 3 and 4 are provided With binding-posts 5 and 6 for the circuitwires 7 and 7. For the convenient location and attachment of these binding-posts the top and bottom plates are preferably flanged, as shown at 8 and 9. In the top 4 of the jar is formed an aperture, through which passes the metallic stem 10, the lower extremity of which is provided with a metallic contact-plate 12, which when the lamp 90 is of normal brilliancy is in direct metallic connection with In order to insure perfect electrical contact between plates 3 and 12 a spring 13, composed of copper or other suitable metal, is preferably employed. This spring is secured to plate 3, and is of such shape that it engages the plate 12 just before it reaches the bottom of the jar or vessel. Perfect metallic contact is thus established between plates 3 and 12, while if it were not for this spring a few grains of sediment in the bottom of the jar might materially interfere with obtaining perfect contact. The top plate 4 is provided with means for supporting the stem 10 and its plate 12 in any desired position between the top and bottom of the jar. In the drawings is shown a simple contrivance for accomplishing this purpose, said means consisting of a pair of springs 15, secured to plate 4 and located on opposite sides of the stem which they engage. These springs are of sufficient strength to support the stem by frictional contact in any desired position. Any other suitable means may, however, be employed to accomplish this purpose. The top of this stem is provided with a button or small knob 16, composed of some suitable insulating material. In this jar is placed aweak solution of some suitable acid, the jar being made liquid-tight for the purpose. The object of the acid is toincrease the electrical conductivity of the water, which possesses this quality to such a low degree that as soon as plates 12 and 3 are separated the lamp is extinguished, while by adding a small quantity of acid this quality of the liquid is sufficiently increased to keep the lamp burning after the plates 3 and 12 are separated. Hence the solution must be so regulated that as soon as plates 3 and 12 are separated or the metallic connection between them broken the brilliancy of the light will diminish. The electrical conductivity of the solution must therefore, it is believed be greater than water and less than metal, while between these two extremes it may be varied at will by the use of more or less acid, as the circumstances of the case may render necessary or desirable. The principle upon which my improved rheostat operates, as well as the manner of using the same, will be readily understood.

As shown in the drawings, the electric current may be said to pass from the electric source through feed-wire 60, branch wire 7, binding-post 6, the top plate f the rheostat, stem 10, contact-plate 12, spring 13, bottom plate 3, binding-post 5, wire 7, through the lamp 90, and theneem'a branch wire 80 to feedwire and back to the other pole of the electrical source. \Vhen part 12 rests upon spring 13, the metallic circuit is uninterrupted outside of the lamp, which is then of normal intensity, brilliancy, or candle-power. Now to decrease the intensity of the light, which is the object of the invention, it is only necessary to break the metallic connection between plates 3 and 12, since the circuit must then be completed through the liquid lying between these plates, the conductivity of the liquid being less than that of the metal, as before stated. The plates 12 and 3 are separated by raising stem 10 until thelamp is regulated as desired. It will thus be seen that by the use of this device the lamp may be regulated or turned down and the light softened or its intensity diminished to any degree desired. The rheostat is given any suitable location in the electric-light circuit, as shown in Fig. 6, and may be secured to the wall of the room by means of flanges 25, secured to the top and bottom plates and suitably insulated from surrounding objects.

The liquid-containing vessel is provided with an opening in the top, through which the solution may be conveniently introduced. This opening may be closed by the use of a screw-plug 20.

Having thus described my invention, what I claim is 1. .The combination, with an incandescentelectric-lam p circuit, of means interposed therein for controlling the brilliancy of the light, said means consisting of a vessel containing a suitable acid solution, said vessel consisting of a body composed of glass or other suitable non-conductor of the electric current, having a metallic top and bottom, a metal stem terminating at its bottom in a suitable metallic contact-plate and passing up through the top of the vessel, said stem being adjustable and the top of the vessel being provided with means for supporting the same in any desired position, the bottom of the vessel being provided with aleaf contact-spring, and the metallic top and bottom parts, each provided with a binding-post to which the circuit-wires respectively lead, substantially as described. 1

2. The combination, with an electric-lamp circuit, of a rheostat interposed therein and consisting of a liquid-containing vessel provided with two stationary metallic parts suitably insulated from each other and to which the circuit-wires respectively lead, a movable metallic plate located between these parts, a metal stem connected with said movable part and passing through one of the stationary metal parts with which it is electrically connected, the other stationary metal part being provided with a contact-spring, and a solution possessing a suitable degree of electrical conductivity, whereby as the metallic circuit is broken the power of the light is diminished by the increased resistance of the intervening liquid, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

WALTER A. STERLING.

\Vitnesses:

WM. MCCONNELL, G. J. ROLLANDET. 

